Liquid crystal alpha-numeric displays are now well known and are shown, for example, in U.S. Pat. No. 3,731,986, issued May 8, 1973. Displays of this type comprise a layer of nematic liquid crystal material sandwiched between a pair of parallel transparent plates, the plates being coated on selected areas thereof with transparent conductive material to form an alpha-numeric display. The surfaces of the plates in contact with the liquid crystal material are treated to effect a twisted-nematic structure. Application of an electrical potential between the transparent conductive coatings will cause the nematic structure to untwist. By providing polarizers on opposite sides of the display, polarized light can be made to pass through the structure or be blocked, depending upon whether the polarizers are crossed or parallel to each other.
In alpha-numeric liquid crystal displays of the type described above, two polarizers are employed, one in front of the display and one behind. This results in black or dark numerals on a light background. In certain cases, however, it is desirable to employ a display which has light numerals or other indicia on a dark background. In the past, it has been very difficult to build such a passive twisted-nematic display with light numerals on a dark background, the reason being that the display cannot receive adequate light through the widely-spaced polarizers to give good contrast under all conditions and lighting situations.